New wireless Internet applications continue to drive the need for increased electromagnetic spectrum utilization in the form of an increase in bandwidth for transmitting data. Service providers and regulators are simultaneously seeking an equivalent increase in spectrum utilization. To address the above ever-present demands, a variety of different wireless networks, i.e. Advanced Mobile Phone System (“AMPS”), Global System Mobile (“GSM”), and Personal Communications Service (“PCS”) were developed to transmit data using different frequencies of the radio spectrum.
In addition, several technologies have been developed for more efficient use of the radio spectrum. For instance, Frequency Division Multiple Access (“FDMA”) is a data transmission technique that allows many cellular telephone users to communicate with one base station by assigning each user a different frequency channel. Code Division Multiple Access (“CDMA”) is a technique that enables cellular telephone users to share a given frequency channel by breaking each transmitted signal into many packets of data, each of which is tagged with the cell phone user's code, wherein the packets are spread over a band of frequencies and then reassembled at the receiving end. Cellular Digital Packet Data (“CDPD”) is another data packet technique similar to CDMA. Orthogonal Frequency Division Multiple access (“OFDM”) is a technique wherein a data message is split into fragments, and using a single transmitting source, the fragments are simultaneously transmitted over a cluster of (adjacent) radio frequency (“RF”) channels with all channels using the same modulation/coding type and controlled by the same protocol rules. Finally, Time Division Multiple Access (“TDMA”) is a technique for channel sharing that assigns each cell phone user a repeating time slot in a frequency channel.
Moreover, the current wireless communications infrastructure as described allows most United States and worldwide cellular regions to provide for multiple independent standards. Some infrastructure base station equipment and client side terminal devices, such as cellular telephones, also have the capability to operate according to multiple standards. Nonetheless, inefficient utilization of the above-described communications infrastructure occurs for a number of reasons.
First, many client side wireless modem devices operate according to only one standard. This is also true for wireline modems. In addition, most wireline base station equipment is incapable of operating according to multiple standards because of the more constrictive electromagnetic nature of copper wire and coaxial cable used with this equipment. Second, although multiple wireless standards may occupy the same region and not interfere with each other, these standards typically occupy principally the same frequencies in the electromagnetic spectrum, or very nearly so. This limits a perspective user to one air standard or another at any given time. Examples include AMPS and CDMA in the same geographical area or GSM and CDMA in the same geographical area. In addition, inefficient utilization may occur due to various interference issues among the above cellular techniques, which may also limit a prospective cellular telephone user to one air standard or another, i.e. limiting use to AMPS, which uses CDPD technique or IS-95, which uses the CDMA technique when both are available in the same region.
Finally, the current hardware used to facilitate wireless communications limits the utilization of the available bandwidth. One such example is presently available multimode radio technology, i.e. iDEN/GSM and ANALOG/CDMA radios and tri-mode cellular telephones. iDEN/GSM and ANALOG/CDMA radios increase the effective footprint of a coverage area by enabling roaming across multiple technologies, and tri-mode phones can operate using three different standards. However, each described unit is only capable of operating according to one standard at a time.
The limitation to one air standard or the other at any given time (in a multiple standard geographic region) prevents both carriers and users from maximizing the utilization of the available infrastructure for wireless data traffic. What is needed are techniques and apparatus that can be used to increase utilization of the existing infrastructure and simultaneously provide users with the greatest possible bandwidth for data traffic given the existing infrastructure.